A power on reset circuit is substantially built in the conventional chip. There are many types of power-on reset circuits. Currently, it is most widely applied that the power on reset (POR) signal is generated by using resistance-capacitance, Schmitt triggers or inverters.
However, when the conventional power on reset circuit converts the level by using the inverter, the anti-interference ability of the conventional power on reset circuit for the power supply disturbance is relatively poor, that is to say, when the power supply jitters near converting the level by the inverter, the inverter will convert the level continually and generate a series of unstable POR signals. Such a phenomenon is called a false triggering, so that the chip cannot work normally. The circuit that uses the Schmitt trigger to convert the level has a certain anti-interference capability. However, it is difficult to set the upper and lower threshold levels of the Schmitt trigger accurately, and the threshold levels vary with the fluctuation of the power supply voltage. Therefore, it is difficult to accurately modulate threshold levels of the power on reset, so that the resulting POR signal is unstable.